Heart failure remains a leading cause of death in the US and worldwide. Maladaptive cardiac remodeling occurs in response to varied insults like ischemia or hemodynamic loads. How this occurs remains incompletely understood, in particular in human hearts. Activation and induction of transcription factors (TFs) often underlies significant phenotypic changes. Identification of TFs induced or repressed in HF would therefore be of great interest. We propose to identify such factors here, using a novel platform for quick, efficient, and inexpensive quantification of the expression of all known and putative transcription factors in the genome. We will use a collection of frozen myocardial samples from >100 human failing hearts, acquired at the time of transplantation and collected over the last 15 years. In addition, in a subset of human post-transplant hearts, primary cardiomyocytes were separated from other cells and frozen, providing the unique opportunity to also test if the altered expression of identified TFs stems from cardiomyocytes or non-cardiomyocytes. The immediate goal of this R21 is to identify candidate TFs that may drive cardiomyopathy in humans. The results of these studies will then be used as foundation for larger mechanistic studies to test the role of identified candidate TFs, using model organisms like mouse and zebrafish. Our long term goal is to identify novel transcription factors and genetic pathways that drive human cardiac heart failure, and that may be amenable to pharmaceutical intervention.